如何检查Request.QueryString是否为空

Question

我有我自己的HandleErrorAttribute,它从读取数据Exception,并HttpContext,将它们插入到模板和发送电子邮件管理员.它通常工作正常,但在某些情况下,它会在尝试检查是否QueryString为空时断开.

var requestParams = "";
if (context.Request.QueryString != null && context.Request.QueryString.Keys.Count > 0)
{
    foreach (String key in context.Request.QueryString.Keys)
    {
        requestParams += key + ": " + context.Request.QueryString[key] + "<br />";
    }
}
else
{
    requestParams = "[ no query string data ]";
}

它在检查condition(NullReferenceException)时会中断,即使我在调试中可以看到,它QueryString不是null并且Keys.Count等于0.

我在这里错过了什么？如何正确检查空QueryString？

堆栈跟踪:

w System.Web.Hosting.IIS7WorkerRequest.GetQueryStringPtr(Int32& length)
w System.Web.Hosting.IIS7WorkerRequest.GetQueryStringRawBytes()
w System.Web.HttpRequest.get_QueryStringBytes()
w System.Web.HttpRequest.FillInQueryStringCollection()
w System.Web.HttpRequest.EnsureQueryString()
w System.Web.HttpRequest.get_QueryString()
w System.Web.HttpRequestWrapper.get_QueryString()
w project.Infrastructure.Attributes.ErrorHandlingAttribute.BuildErrorEmail(Exception exc, HttpContextBase context) w c:\Users\Marcin Bigoraj\Documents\Visual Studio 2012\Projects\project\Infrastructure\Attributes\ErrorHandlingAttribute.cs:wiersz 141
w project.Infrastructure.Attributes.ErrorHandlingAttribute.<>c__DisplayClass2.<OnException>b__1() w c:\Users\Marcin Bigoraj\Documents\Visual Studio 2012\Projects\project\Infrastructure\Attributes\ErrorHandlingAttribute.cs:wiersz 182
w System.Threading.Tasks.Task.InnerInvoke()
w System.Threading.Tasks.Task.Execute()

Answer 1

检查此代码

if (Request.QueryString.Keys.Count > 0)
{

}